PNG writer

apps/LoopThroughWithOpenGLCompositing/gl/OpenGLComposite.cpp

@@ -6,10 +6,17 @@
 #include "OpenGLDeckLinkBridge.h"
 #include "OpenGLRenderPass.h"
 #include "OpenGLShaderPrograms.h"
+#include "PngScreenshotWriter.h"
 #include "RuntimeServices.h"
 #include "ShaderBuildQueue.h"
 
+#include <algorithm>
+#include <chrono>
+#include <ctime>
+#include <filesystem>
+#include <iomanip>
 #include <memory>
+#include <sstream>
 #include <string>
 #include <vector>
 
@@ -17,7 +24,8 @@ OpenGLComposite::OpenGLComposite(HWND hWnd, HDC hDC, HGLRC hRC) :
 	hGLWnd(hWnd), hGLDC(hDC), hGLRC(hRC),
 	mDeckLink(std::make_unique<DeckLinkSession>()),
 	mRenderer(std::make_unique<OpenGLRenderer>()),
-	mUseCommittedLayerStates(false)
+	mUseCommittedLayerStates(false),
+	mScreenshotRequested(false)
 {
 	InitializeCriticalSection(&pMutex);
 	mRuntimeHost = std::make_unique<RuntimeHost>();
@@ -29,6 +37,7 @@ OpenGLComposite::OpenGLComposite(HWND hWnd, HDC hDC, HGLRC hRC) :
 		hGLDC,
 		hGLRC,
 		[this]() { renderEffect(); },
+		[this]() { ProcessScreenshotRequest(); },
 		[this]() { paintGL(); });
 	mRenderPass = std::make_unique<OpenGLRenderPass>(*mRenderer);
 	mShaderPrograms = std::make_unique<OpenGLShaderPrograms>(*mRenderer, *mRuntimeHost);
@@ -283,6 +292,13 @@ bool OpenGLComposite::ReloadShader()
 	return true;
 }
 
+bool OpenGLComposite::RequestScreenshot(std::string& error)
+{
+	(void)error;
+	mScreenshotRequested.store(true);
+	return true;
+}
+
 void OpenGLComposite::renderEffect()
 {
 	ProcessRuntimePollResults();
@@ -324,6 +340,69 @@ void OpenGLComposite::renderEffect()
 		});
 }
 
+void OpenGLComposite::ProcessScreenshotRequest()
+{
+	if (!mScreenshotRequested.exchange(false))
+		return;
+
+	const unsigned width = mDeckLink ? mDeckLink->OutputFrameWidth() : 0;
+	const unsigned height = mDeckLink ? mDeckLink->OutputFrameHeight() : 0;
+	if (width == 0 || height == 0)
+		return;
+
+	std::vector<unsigned char> bottomUpPixels(static_cast<std::size_t>(width) * height * 4);
+	std::vector<unsigned char> topDownPixels(bottomUpPixels.size());
+
+	glBindFramebuffer(GL_READ_FRAMEBUFFER, mRenderer->OutputFramebuffer());
+	glReadBuffer(GL_COLOR_ATTACHMENT0);
+	glPixelStorei(GL_PACK_ALIGNMENT, 1);
+	glPixelStorei(GL_PACK_ROW_LENGTH, 0);
+	glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, bottomUpPixels.data());
+	glPixelStorei(GL_PACK_ALIGNMENT, 4);
+
+	const std::size_t rowBytes = static_cast<std::size_t>(width) * 4;
+	for (unsigned y = 0; y < height; ++y)
+	{
+		const unsigned sourceY = height - 1 - y;
+		std::copy(
+			bottomUpPixels.begin() + static_cast<std::ptrdiff_t>(sourceY * rowBytes),
+			bottomUpPixels.begin() + static_cast<std::ptrdiff_t>((sourceY + 1) * rowBytes),
+			topDownPixels.begin() + static_cast<std::ptrdiff_t>(y * rowBytes));
+	}
+
+	try
+	{
+		const std::filesystem::path outputPath = BuildScreenshotPath();
+		std::filesystem::create_directories(outputPath.parent_path());
+		WritePngFileAsync(outputPath, width, height, std::move(topDownPixels));
+	}
+	catch (const std::exception& exception)
+	{
+		OutputDebugStringA((std::string("Screenshot request failed: ") + exception.what() + "\n").c_str());
+	}
+}
+
+std::filesystem::path OpenGLComposite::BuildScreenshotPath() const
+{
+	const std::filesystem::path root = mRuntimeHost && !mRuntimeHost->GetRuntimeRoot().empty()
+		? mRuntimeHost->GetRuntimeRoot()
+		: std::filesystem::current_path();
+
+	const auto now = std::chrono::system_clock::now();
+	const auto milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch()) % 1000;
+	const std::time_t nowTime = std::chrono::system_clock::to_time_t(now);
+	std::tm localTime = {};
+	localtime_s(&localTime, &nowTime);
+
+	std::ostringstream filename;
+	filename << "video-shader-toys-"
+		<< std::put_time(&localTime, "%Y%m%d-%H%M%S")
+		<< "-" << std::setw(3) << std::setfill('0') << milliseconds.count()
+		<< ".png";
+
+	return root / "screenshots" / filename.str();
+}
+
 bool OpenGLComposite::ProcessRuntimePollResults()
 {
 	if (!mRuntimeHost || !mRuntimeServices)